Synthesis of functionalized imidazo[4,5-e]thiazolo[3,2-b]triazines by condensation of imidazo[4,5-e]triazinethiones with DMAD or DEAD and rearrangement to imidazo[4,5-e]thiazolo[2,3-c]triazines

• Alexei N. Izmest’ev,
• Dmitry B. Vinogradov,
• Natalya G. Kolotyrkina,
• Angelina N. Kravchenko and
• Galina A. Gazieva

Beilstein J. Org. Chem. 2021, 17, 1141–1148, doi:10.3762/bjoc.17.87

• also Supporting Information File 1 for details). The reaction of 5,7-dimethylimidazo[4,5-e]triazine-3-thione (3a) with DEAD proceeded in alcohols with moderate regioselectivity and isomer 5 predominated in the filtered precipitates (Table 1, entries 1–3). The use of absolute or 95% ethanol as a solvent

• 1,3-diethylimidazo[4,5-e]thiazolo[3,2-b]triazines 4a,b,h,i upon treatment with an equivalent amount of triethylamine in corresponding alcohols proceeded without hydrolysis of ester groups and led to the formation of the corresponding regioisomeric derivatives 5a,b,h,i (Scheme 4). The isomerization of

• imidazo[4,5-e]thiazolo[3,2-b]triazines 4c–g,j–n bearing phenyl groups occurred only upon refluxing the starting compounds in corresponding alcohols in the presence of sodium alcoholates. Imidazo[4,5-e]thiazolo[2,3-c]triazines 5a–n were synthesized in yields of 58–91%. Because the reaction of imidazo[4,5-e

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

• -amino ketone derivative 124 in high yield and diastereoselectivity (Scheme 34). A reduction of 124 gave a mixture of diastereomeric alcohols, and the one with (R)-configuration at the benzylic position was isolated in 54% yield. Further treatment of the alcohol with NaH furnished a cyclized product

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

• 1888 it was discovered that heating a mixture of cyanoguanidine and amine hydrochloride in a polar solvent (mainly alcohols) led to the formation of biguanide. Indeed, proton exchanges at high temperatures may lead to the activation of cyanoguanidine by protonation, and the subsequent attack of the

Stereoselective synthesis and transformation of pinane-based 2-amino-1,3-diols

• Ákos Bajtel,
• Mounir Raji,
• Matti Haukka,
• Ferenc Fülöp and
• Zsolt Szakonyi

Beilstein J. Org. Chem. 2021, 17, 983–990, doi:10.3762/bjoc.17.80

• synthesize novel, cyclic potentially analogues of sphingosine, incorporating a lipophilic natural pinane skeleton, starting from commercially available monoterpene-based allylic alcohols via a stereoselective hydroxyamination in the presence of a potassium osmate(VI) catalyst. We also planned to explore the

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

• Krista Gulbe,
• Jevgeņija Lugiņina,
• Edijs Jansons,
• Artis Kinens and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 964–976, doi:10.3762/bjoc.17.78

• -glycosides to demonstrate the scope of acceptors compatible with our glycosylation conditions (Scheme 1). Most of the primary alcohols (2a, 2d–3f) were glycosylated in high yields (up to 91%). In the case of less reactive secondary alcohols (2b, 2h, 2j, 2k) and phenol (2l) better yields were obtained when

• corresponding alcohols were slightly higher (up to 95%). By employing 2-phenylethanethiol (2c), a gram-scale synthesis of mannoside 3c was successfully demonstrated. Diminished reactivity towards glycosylation of some alcohols (2g, 2i, 2r) in liquid SO2 can be explained by possible formation of stable

• carbocation species [52]. Thus, in contrast to the other primary alcohols, an excess of 3.0 equiv was required to provide a moderate 62% yield of mannoside 3g when benzyl alcohol (2g) was used as an acceptor. Next, the formation of tertiary carbenium ion from 3-methyl-butan-2-ol (2i) via 1,2-hydrogen shift in

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• major drawbacks identified with the Prins cyclization are the racemization due to competing oxonia-Cope rearrangement and side-chain exchange. Willis and co-workers studied the reactivity of the Prins reaction of different aryl group-substituted homoallylic alcohols 18 with propanal in the presence of a

• Lewis acid, which furnished the expected tetrahydropyran 23 as a single diastereomer via an oxocarbenium intermediate 21 (Scheme 5) [29][30]. The reaction was dependent from the nature of the aromatic ring, which plays a crucial role in the product formation. Homoallylic alcohols with an electron-rich

• alcohols having unactivated and unsubstituted alkenes, whereas the substituent adjacent to the hydroxy group in the homoallylic alcohol controls the oxonia-Cope rearrangement (see 273a–c). The alkyl substituent favored the exclusive formation of crossed THP derivatives, whereas 2-oxonia-Cope rearrangement

Manganese/bipyridine-catalyzed non-directed C(sp³)–H bromination using NBS and TMSN₃

• Kumar Sneh,
• Takeru Torigoe and
• Yoichiro Kuninobu

Beilstein J. Org. Chem. 2021, 17, 885–890, doi:10.3762/bjoc.17.74

• alcohols with HBr, PBr3, or other brominating reagents [7][8][9][10][11][12][13]. Direct C–H halogenation is one of the most efficient methods used for the synthesis of halogenated organic molecules. This direct method involves the reaction of an alkane with Br2, CBr4, or H2O2–HBr under photolysis or at

Kinetics of enzyme-catalysed desymmetrisation of prochiral substrates: product enantiomeric excess is not always constant

• Peter J. Halling

Beilstein J. Org. Chem. 2021, 17, 873–884, doi:10.3762/bjoc.17.73

• are the reduction of prochiral ketones to chiral secondary alcohols, transamination of prochiral ketones to chiral amines, hydrolysis of symmetrical diesters to a chiral monoester, and esterification of prochiral diacids or diols. In desymmetrisation reactions, the enzyme initially produces the two

Synthesis of bis(aryloxy)fluoromethanes using a heterodihalocarbene strategy

• Carl Recsei and
• Yaniv Barda

Beilstein J. Org. Chem. 2021, 17, 813–818, doi:10.3762/bjoc.17.70

• . An attempt to react dibromofluoromethane with n-pentanol in the presence of potassium hydroxide or sodium tert-butoxide did not produce di(n-pentoxy)fluoromethane at ambient temperature. Since elevated temperatures are typically required for the direct, SN2 attack upon dibromomethanes by alcohols or

A chromatography-free and aqueous waste-free process for thioamide preparation with Lawesson’s reagent

• Ke Wu,
• Yichen Ling,
• An Ding,
• Liqun Jin,
• Nan Sun,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2021, 17, 805–812, doi:10.3762/bjoc.17.69

• reckoned that converting compound A to a more polar derivative could probably be a breakthrough. As common knowledge, the more polarized alcohols over EtOH are those diols or polyols, while MeOH was previously ruled out. Ethylene glycol, a basic chemical and the simplest diol, is slightly soluble in

Chiral isothiourea-catalyzed kinetic resolution of 4-hydroxy[2.2]paracyclophane

• David Weinzierl and
• Mario Waser

Beilstein J. Org. Chem. 2021, 17, 800–804, doi:10.3762/bjoc.17.68

• successfully used for the kinetic resolution of different racemic alcohols [33][34][35][36][37]. Inspired by this unique catalysis potential, we therefore became interested in testing those chiral catalysts for the, to the best of our knowledge, so far not investigated acylative kinetic resolution of 4-hydroxy

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• conditions. For instance, for polyesters, alcoholysis may provide mixed monomers formally derived from transesterification reactions [89][90], while aminolysis provides amides and alcohols [91][92]. In the search of “greener” technologies for plastic recycling, catalytic hydrogenolysis processes have been

• accounts for around 8% by weight and 12% by volume of the world's solid waste [159][160]. PET is a copolymer of terephthalic acid (TPA) and EG [161]. It is best soluble in chlorophenol, tetrachloroethane, m-cresol, NMP, nitrobenzene and 1,1,1,3,3,3-hexafluoro-2-propanol, insoluble in common alcohols and

Synthesis of (Z)-3-[amino(phenyl)methylidene]-1,3-dihydro-2H-indol-2-ones using an Eschenmoser coupling reaction

• Lukáš Marek,
• Lukáš Kolman,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2021, 17, 527–539, doi:10.3762/bjoc.17.47

• , like DMSO or DMF or in polar protic solvents like alcohols. For carbon acids the ΔpKa is 12.9 between ACN and DMSO but the ΔpKa is only −1.5 between DMF and DMSO [34]. A change of the solvent from acetonitrile to DMF should therefore decrease the pKa by ca. 11 units. In polar protic solvents (e.g., in

A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles

• Lucía Rossi-Fernández,
• Viviana Dorn and
• Gabriel Radivoy

Beilstein J. Org. Chem. 2021, 17, 519–526, doi:10.3762/bjoc.17.46

• and industrial applications [1]. Among them, allylic oxidation and olefin epoxidation constitute fundamental tools for the synthesis of homoallylic alcohols or α,β-unsaturated carbonyl compounds, and epoxides, respectively. In particular, epoxides are pivotal building blocks for the synthetic chemists

Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

Beilstein J. Org. Chem. 2021, 17, 461–484, doi:10.3762/bjoc.17.41

• phosphonodepsipeptides 56 and 57, respectively. The oxidative activation was carried out in the presence of alcohols as nucleophiles so that stoichiometric formation of the phosphonochloridate was avoided and side reactions were minimized (Scheme 9) [25]. The current chlorination is a mild and neutral method for the

• reactive toward alcohols (hydroxy esters) than toward amines (amino esters), contrary to their carboxylic partners (Scheme 19) [34]. The coupling reagents BroP and N,N,N',N'-bis(tetramethylene)chlorouronium tetrafluoroborate (TPyCIU) were applied as activating agents in the synthesis of

1,2,3-Triazoles as leaving groups: S_NAr reactions of 2,6-bistriazolylpurines with O- and C-nucleophiles

• Dace Cīrule,
• Irina Novosjolova,
• Ērika Bizdēna and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 410–419, doi:10.3762/bjoc.17.37

• -nucleophiles [12][13][14] and in metal catalyzed reactions of halopurine derivatives [15][16][17][18][19][20]. Modifications of purines with O-nucleophiles are based on SNAr reactions between 6-halopurine derivatives and alcohols [21][22][23][24][25][26][27][28] in the presence of a base. Alcohols are used in

• first performed on N9-alkylated bistriazole 2c. The reactions were carried out with primary and secondary alcohols in the presence of NaH in DMF. The developed transformation required only nearly equimolar loading of an alcohol and a base, and products 3a–f were obtained in yields up to 83% (Scheme 3

• transformations requires heating the reaction mixtures up to 60 °C for 24 h. An SNAr reaction with a non-trivial alcohol was demonstrated on the example of 2',3'-O-isopropylideneuridine and product 3f was isolated after 21 h of heating at 50 °C in 82% yield. It should be noted that tertiary alcohols (e.g., t-BuOH

Mesoionic tetrazolium-5-aminides: Synthesis, molecular and crystal structures, UV–vis spectra, and DFT calculations

• Vladislav A. Budevich,
• Sergei V. Voitekhovich,
• Alexander V. Zuraev,
• Vadim E. Matulis,
• Vitaly E. Matulis,
• Alexander S. Lyakhov,
• Ludmila S. Ivashkevich and
• Oleg A. Ivashkevich

Beilstein J. Org. Chem. 2021, 17, 385–395, doi:10.3762/bjoc.17.34

• various organic solvents, such as alcohols, chloroform, dichloromethane, hexane, acetonitrile, toluene, and THF. They are also soluble in water. Remarkably, the solutions in organic solutions are yellow colored, whereas aqueous solutions are colorless. The UV–vis spectra of 8a were found to show

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

• hyperconjugation and/or fluorine lone pair interaction, resulting in a certain degree of a positive charge of one fluorine atom. Interestingly, at least one phenyl substituent was required to allow the ionization of the starting alcohols into the corresponding carbenium ions. When the aromatic substituent was

• absent or upon installation of an additional CF3 group, only the corresponding protonated alcohols 10d–g were observed. Olah et al. also reported the 13C NMR chemical shifts for carbenium ion 10c upon ionization of the alcohol precursor 9c in a superacid (Scheme 4) [36]. A large downfield shift was

• alcohols was shown by Cohen and Kaluszyner [55][56] and by Streitwieser et al. [57]. The cyclodehydration of 9c occurs in polyphosphoric acid to afford fluorene 37 (Scheme 8) [57]. A mechanistic proposal invoking the initial generation of the α-(trifluoromethyl)carbenium ion 10c↔10c’ was mentioned by the

Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases

• Olga Gherbovet,
• Fernando Ferreira,
• Apolline Clément,
• Mélanie Ragon,
• Julien Durand,
• Sophie Bozonnet,
• Michael J. O'Donohue and
• Régis Fauré

Beilstein J. Org. Chem. 2021, 17, 325–333, doi:10.3762/bjoc.17.30

• regioselectivity of transesterifications of hydroxylated alkyl and/or aryl moieties are sparser [26][34][35][36]. The extent to which Lipozyme® TL IM catalyzes feruloyl transfer reactions involving substituted benzylic alcohols was thus investigated to establish its usefulness for the preparation of both various

• polyhydroxylated molecules of interest (e.g., antioxidants) [4][26] and of novel chromogenic feruloylated substrates with various physicochemical features for screening applications. Accordingly, we observed that transesterifications only occurred when using primary benzylic alcohols; no phenol acylation was

• alcohols and polyhydroxylated compounds. Three compounds suitable for the detection and/or characterization of Fae activity were synthesized in a straightforward protocol that holds the potential to greatly reduce the cost of the substrates 1a and 1b. Moreover, the enzyme-driven convergent synthesis of 12

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• hydrogenolysis of benzyl ethers (H2, Pd) [72], DIBAL-H reduction of esters to form alcohols [73], oxidative cleavage of vinyl groups to form carboxylic acids (KMnO4) [74], and the conversion of the acids into amines using the Curtius rearrangement (SOCl2, followed by Me3SiN3, thermolysis, and acid hydrolysis of

• alcohols, ethers, esters, and amines (121, Scheme 53) [103]. They proposed that an initial tin–lithium exchange was followed by a β-elimination of LiF to form the intermediate cyclopropenes 119. The ring opening of the latter then generated the vinylcarbenes 120. The carbenes 120 could then insert into the

• O–H and N–H bonds of water, alcohols, carboxylic acids, and amines to form the observed products 121. 1,1-Difluoro-2-siloxy-2-vinylcyclopropane (122) was subjected to a fluoride-catalyzed ring opening to afford 1-fluorovinyl vinyl ketones such as 123. These compounds underwent a Lewis acid-catalyzed

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• between thiol-functionalized β-CD and oleic acid-protected CdS nanocrystals [29]. These spherical CdS–CD nanoparticles could be employed as a photocatalyst for the dehydrogenation of alcohols to aldehydes (at a low concentration of the reactant of 1 mM, ≥92% selectivity) or diols (at a high concentration

• benzaldehyde by CdS–CD. This figure has been published in CCS Chemistry [2020]; [β-Cyclodextrin Decorated CdS Nanocrystals Boosting the Photocatalytic Conversion of Alcohols] is available online at [DOI; https://www.chinesechemsoc.org/doi/10.31635/ccschem.020.201900093]. (a) Structures of CDs, (b) CoPyS, and

Facile preparation and conversion of 4,4,4-trifluorobut-2-yn-1-ones to aromatic and heteroaromatic compounds

• Takashi Yamazaki,
• Yoh Nakajima,
• Minato Iida and
• Tomoko Kawasaki-Takasuka

Beilstein J. Org. Chem. 2021, 17, 132–138, doi:10.3762/bjoc.17.14

• -ones by the oxidation of the readily accessible corresponding propargylic alcohols as well as their utilization as Michael acceptors for the construction of aromatic and heteroaromatic compounds are reported. Keywords: CF3-containing propargylic alcohols; CF3-containing ynones; oxidation; pyrimidines

• group is an important task. During our research in the field of fluorine chemistry, we have previously developed methods to get convenient access to CF3-containing propargylic alcohols 1 using 2-bromo-3,3,3-trifluoropropene [4][5] as well as 1-chloro-3,3,3-trifluoropropene [6] as a substrate and to

• utilize 1 by way of a variety of routes [7][8][9][10][11][12][13][14]. Recently, we turned our attention to oxidized propargyl alcohols, namely ynones 2, because of the interesting structure with two strongly electron-withdrawing moieties, resulting in a high electrophilicity. However, only a few methods

Synthesis of aryl 2-bromo-2-chloro-1,1-difluoroethyl ethers through the base-mediated reaction between phenols and halothane

• Yukiko Karuo,
• Ayaka Kametani,
• Atsushi Tarui,
• Kazuyuki Sato,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2021, 17, 89–96, doi:10.3762/bjoc.17.9

• carbon that was explained by an orbital interaction between the n orbital (fluorine) and the π orbital [44]. A literature survey revealed that Yagupol’skii et al. have achieved the first synthesis of aryl or alkyl 2-bromo-2-chloro-1,1-difluoroethyl ethers by the reaction of alcohols with halothane as

Benzothiazolium salts as reagents for the deoxygenative perfluoroalkylthiolation of alcohols

• Armin Ariamajd,
• Nils J. Gerwien,
• Benjamin Schwabe,
• Stefan Dix and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2021, 17, 83–88, doi:10.3762/bjoc.17.8

• directly from readily available alcohols. Keywords: alcohols; benzothiazolium salts; deoxygenative reactions; fluorine; perfluoroalkylthiolation; thioethers; Introduction The incorporation of fluorine-containing groups into organic molecules to modulate their biological or physical properties is nowadays

• reactions of readily available aliphatic alcohols. Some features of this process led us to consider whether related benzothiazolium salts featuring longer-chain SRF substituents could serve as practical reagents for investigating nucleophilic perfluoroalkylthiolation reactions. Firstly, the simple two-step

• - and heptafluoropropylthiolation reactions directly from alcohols (Scheme 1c). Results and Discussion Five BT-SRF reagents were selected to provide a good overview on the reactivity of different perfluoroalkylthio groups; four linear BT-SRF derivatives (BT-SC2F5, BT-SC3F7, BT-SC5F11 and BT-SC8F17) and

Progress in the total synthesis of inthomycins

• Bidyut Kumar Senapati

Beilstein J. Org. Chem. 2021, 17, 58–82, doi:10.3762/bjoc.17.7

• using a four-step sequence such as Negishi’s (Z) and (E)-stereoselective isomerization of the terminal alkyne followed by iodinolysis [19][70][71], oxidation to the corresponding aldehydes and enantioselective Kiyooka–Mukaiyama aldol reaction followed by TES protection of the resulting alcohols (Scheme